Cryptanalysis of ISO/IEC 9796-1

We describe two different attacks against the iso/iec 9796-1 signature standard for RSA and Rabin. Both attacks consist in an existential forgery under a chosen-message attack: the attacker asks for the signature of some messages of his choice, and is then able to produce the signature of a message that was never signed by the legitimate signer. The first attack is a variant of Desmedt and Odlyzko's attack and requires a few hundreds of signatures. The second attack is more powerful and requires only three signatures. Key-words: Cryptanalysis, iso/iec 9796-1 signature standard, RSA signatures, Rabin signatures, encoding scheme.

• Type: Journal
• Year: 2008
• Where: JOC
• Authors: Don Coppersmith, Jean-Sébastien Coron, François Grieu, Shai Halevi, Charanjit S. Jutla, David Naccache, Julien P. Stern
• Keywords: Existential Forgery, JOC 2008, Signature Standard, Signatures